Liquid crystal display devices are used not only for large-sized television sets but also as small-sized display devices in the display sections of mobile phones or the like, and there are needs for further thinner liquid crystal display devices in recent years. When a light source which is provided in a liquid crystal display device for achieving a high contrast ratio is disposed directly under the liquid crystal panel, the liquid crystal display device will become thick. Therefore, liquid crystal display devices have been proposed whose light source is provided on a lateral side of the liquid crystal panel (see, for example, Patent Documents 1 and 2).
FIG. 6 shows a schematic diagram of a liquid crystal display device 800 which is disclosed in Patent Document 1. The liquid crystal display device 800 includes a liquid crystal panel 810 and a sidelight unit 820 provided on a lateral side of the liquid crystal panel 810. Light which is emitted from a fluorescent lamp 822 in the sidelight unit 820 enters a glass substrate 812 of the liquid crystal panel 810, and displaying is performed by utilizing this light. A reflector 826 for enhancing the efficiency of utility of light emitted from the fluorescent lamp 822 is provided for the sidelight unit 820. Moreover, a light-scattering type liquid crystal layer 816 is provided for the liquid crystal panel 810 for an increased efficiency of utility of light in the liquid crystal display device 800, without requiring a polarizer.
FIG. 7 shows a schematic diagram of a liquid crystal display device 900 which is disclosed in Patent Document 2. The liquid crystal display device 900 includes a liquid crystal panel 910 and a sidelight unit 920 provided on a lateral side of the liquid crystal panel 910.
Light which is emitted from a fluorescent lamp 922 in the sidelight unit 920 propagates through a light guide plate 924 either directly or after being reflected by a reflector 926, and enters a glass substrate 912 of the liquid crystal panel 910. The liquid crystal panel 910 performs displaying by utilizing this light. The fluorescent lamp 922 is thicker than the glass substrate 912. A rear face 924b of the light guide plate 924 is parallel to the peak direction of the light which is emitted from the fluorescent lamp 922, whereas a front face 924a is provided so as to be inclined with respect to the rear face 924b, and an incident face 924i of the light guide plate 924 that opposes the fluorescent lamp 922 is thicker than an outgoing face 924o opposing the glass substrate 912. Therefore, light which is emitted from the fluorescent lamp 922 enters the thick incident face 924i of the light guide plate 924, and efficiently enters the glass substrate 912 via the thin outgoing face 924o. Moreover, protrusions are provided on the front face 924a and rear face 924b of the light guide plate 924, thus allowing light propagating through the light guide plate 924 to efficiently enter the glass substrate 912.
A film 932 provided on the glass substrate 912 of the liquid crystal panel 910 reflects light entering from the sidelight unit 920 in the lower direction. The light reflected from the film 932 passes through the liquid crystal layer 916, undergoes diffuse reflection at diffuse reflection electrodes 918, and again passes through the liquid crystal layer 916. Light modulation occurs in the liquid crystal layer 916. Thereafter, a polarizer 934 provided on the glass substrate 912 transmits light of a specific polarization component. In this manner, the liquid crystal display device 900 performs displaying.